1. Field of the Invention
The present invention relates to an antenna, and more particularly, to an antenna having a metamaterial superstrate and providing gain improvement and beamforming together.
2. Description of the Related Art
An array antenna, which may be formed by arranging a plurality of patch antennas, is generally used in cases where high-gain radiation characteristics and beam formation are necessary, such as in a base station.
However, as the number of array elements in an array antenna increases, energy loss due to antenna feeds also increases in proportion to the number of antenna feed points. Thus, overall efficiency of an antenna is decreased. Furthermore, it is necessary to precisely adjust both intervals between patch antennas and phases of signals fed to the patch antennas to obtain suitable gain and radiation pattern. Thus, the structure of such an array antenna becomes complicated.
Examples of antennas having higher antenna gain include an electromagnetic bandgap (EBG) type antenna, which is formed by arranging high-k materials in a predetermined interval on top of the antenna, and an antenna of Fabry-Perot resonator, which is formed by disposing a dielectric substrate of a metallic periodic structure on a typical patch antenna.
Such antennas have advantages of a simple feed structure and gain increase using a single feed point compared to that of an array antenna, but have a difficulty in beamforming.